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HD Today: HDV Today, AVC-HD Tomorrow?
Posted Feb 28, 2007 Print Version     Page 1of 1

On May 11, 2006, Panasonic and Sony announced specifications for AVC-HD, a brand new HD digital video camera recorder format the two companies jointly established. The AVC-HD format allows for recording and playback of high-resolution, digital HD images using 8cm DVD media, flash media, and hard disk. AVC-HD employs MPEG-4 AVC/H.264 for video compression, and Dolby Digital (AC-3) or Linear PCM for audio codec. The AVC (Advanced Video Compression) nomenclature for MPEG-4/H.264 is where the AVC-HD name originates. The MPEG-4/H.264 codec is more than twice as efficient as MPEG-2 technology. Sony immediately started to manufacture AVC-HD camcorders for the consumer market (beginning with the UX1 we reviewed in November), first utilizing the 8cm DVD as the recording medium, and then recording to internal hard drives. These hard-drive camcorders offer considerably more space than the 27-minute 8cm DVDs, and Sony decided to up the data rate to improve image quality—from 12Mbps to a max of 15Mbps—but that's at the highest setting. You can dial it down to 9, 7, or 5Mbps.

It doesn't take a genius to guess that 1080i HD video crammed down to 5Mbps will look like heavily compressed video, AVC notwithstanding. Another downside to AVC-HD is that it is a LongGOP structure, using interframe compression like the MPEG-2 codec used in HDV. It is more difficult for computers to handle than DV, because only a portion of the image data in most frames is stored within those frames (see Ben Balser's Editing HDV). Panasonic finally started shipping AVC-HD consumer camcorders at the end of 2006. They also decided to make use of the AVC-HD codec with their P2 media and announced that users would be able to record far more on a single card through the use of an "AVC-Intra" codec—where AVC compression is used, but all the frames are standalone I-Frames. Their first camcorder with this AVC-Intra codec, out in December 2006, was the AJ-JPX2000—a $27,000 model designed for ENG and broadcast use.

I had an opportunity to talk with other event videographers from around the country recently about what kind of pricing makes a camcorder affordable to our market. Outside of major cities, where one can command higher freelance and event prices, it is unlikely that these new camcorders will be found in any of our gear bags. Some pundits have called AVC-Intra the death knell for HDV. But manufacturers are aiming AVC-Intra at a much higher-end clientele than HDV. While we strive to produce quality productions, our clients have yet to demand full-raster 1920x1080, 10-bit video, 4:2:2 in a 100Mbps stream, or 1440x1080, 10-bit video, 4:2:0 in a 50Mbps stream. So far HDV's 8-bit, 1440x1080, 4:2:0 video compressed into a 25Mbps stream has served us well.

In fact, the two most challenging aspects of HDV are not even much of a problem any more. First, some say that the LongGOP structure of HDV makes it difficult to edit, but hardware and software solutions that transcode the HDV video to an all I-Frame codec during capture solve this problem. Even the free iMovie HD from Apple was transcoding HDV to the Apple Intermediate Codec back in 2005. It did this on-the-fly, while digitizing, on a single-chip PowerPC system, long before the move to multicore Intel chips. Intermediate codecs offer faster editing, more real-time capability, and less compression artifacts from processing and re-processing footage.

Many systems edit HDV natively, which means processing up to six times as many pixels per frame as DV. But today's processors continue to offer more performance, and much of today's software is leveraging the Graphics Processing Unit (GPU) on today's powerful video cards for even more dramatic increases in performance. True, HDV remains more processor-intensive than DV, but today's processors can handle more than what DV throws at them.

HDV, as highly compressed, tape-based, and clunky as it is, works well for events precisely because it uses existing and inexpensive DV tape. With an HDV deck, you can record hours of switched master concert footage or that big year-end church celebration on a single tape, and as soon as it is over, you have a high-definition master tape you can put on the shelf till you need to edit it. A 276-minute Advanced Master Quality Panasonic tape (large-shell DV) is $18. The same-length Digital Master Sony is $37. That's over 4.5 hours of continuous tape, HDV or DV.

HDV has one additional advantage that enables it to be the transition format for event videographers: it also does DV. Every camcorder and every deck released is switchable between DV and HDV. Camcorder manufacturers have kept the same batteries. Size and weight of HDV is not that far from similar DV camcorders, so established video producers can ease their way into HDV, while also using the new gear for current DV productions. So for every videographer looking to dip his or her toe in the HD water, HDV provides a solid piece of DV gear that also does HD. It is nice to know that, should we ever need it, high-end gear will be available at rental houses and nonlinear systems will eventually support all those new variations and codecs. But for now, and for the foreseeable future, HDV serves the event video producer just fine.

Anthony Burokas of IEBA Communications, a self-confessed "gadget guy," has been an event videographer for more than 15 years. He has shot award-winning video internationally and is technical director for the PBS series Flavors of America.

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